Modern optical communication networks conveniently employ multi-channel wavelength-multiplexed optical signals. Such signals are comprised of a plurality of spectral channels, each having a distinct center wavelength and an associated bandwidth. The center wavelengths of adjacent channels are spaced at a predetermined wavelength or frequency interval, and the plurality of spectral channels may be wavelength division multiplexed (WDM) to form a composite multi-channel, or WDM, signal of the optical network. Each spectral channel, also referred to herein as the wavelength channel or simply the wavelength, is capable of carrying separate and independent information. At optical switching nodes in the optical network, one or more spectral channels may be dropped from or added to the WDM optical signal, as by using, for example, a reconfigurable optical add-drop multiplexer (ROADM).
A ROADM at the optical switching node may be constructed using one or more wavelength selective switches (WSS) configured as ADD and/or DROP modules. Wavelength selective switching in telecommunications networks is a relatively new technology that enables agility at the physical, i.e. optical, layer of the network. It allows wavelengths carrying data of any protocol or at any rate to be quickly and dynamically re-directed through networks to accommodate changes in demand for bandwidth, or changes in network topology, such as due to addition of new nodes to the network, addition of new wavelengths or services to the network, failures of links or nodes within the network, etc. Examples of WSS and ROADM devices are disclosed in U.S. Pat. Nos. 6,487,334; 6,498,872; 6,549,699, 6,625,346, 6,661,948, 6,687,431, 6,760,511 6,707,959; 7,039,267; 7,027,684; 7,302,134; 7,236,660; 7,212,704, which are incorporated herein by reference.
WSS technology that is available today supports switching of 80 or more channels through a single device, with the port count of a typical WSS being between typcially 3 and 10 or even greater. One type of WSS devices conveniently used today has one ‘common’ port, while all others are ‘add/drop’ ports, where each supported wavelength can be routed between the common port and any one, and typically only one, of the add/drop ports, or ‘blocked’ entirely (i.e., highly attenuated). However, this or similar technology could be extended to support much greater numbers of wavelengths and ports, or to support the ability to route wavelengths between any two ports. Note that WSSs are typically bi-directional in nature. That is, once the path for a given wavelength through the WSS has been configured from one port to another, modulated or unmodulated light of that wavelength can propagate in either direction between the two ports.
Advantageously, WSS technology enables reconfiguration of wavelength paths through networks using software control, without the need for technicians to change physical connections between devices in the network, such as to change optical fibre connections between fixed optical multiplexer/demultiplexer devices at network nodes where wavelengths are being added to or dropped from the optical network. However, despite the existence of the ability to perform wavelength reconfiguration remotely, control of telecommunications networks today still often relies on human intervention to determine the optimal wavelength configuration, and then to implement or initiate the desired change.
Human intervention may be particularly intense during deployment and commissioning of new WSS devices in a network, when operators must typically configure each supported wavelength. In some cases, network-level control software is used to reduce this burden by allowing the operator to configure a wavelength path through the entire network, and automating the configuration of individual WSS devices and ROADM nodes within the network.
However, this approach may also have certain disadvantages. In particular, smaller and simpler networks involving WSS/ROADM technology often don't warrant the increased cost and complexity of this network level control. Furthermore, network-level wavelength configuration approach necessitates having a computer or server that requires continuous software access to all nodes in the network in order to re-configure it. Furthermore, network operators may want to be able to introduce WSS or ROADM technology into existing networks without having to entirely change the method in which the network is managed, or to reconfigure the network management software at the control node.
Accordingly, a solution is desired that would enable to automate, or reduce the burden of, configuring WSS devices at the individual WSS device or network element (network node) level without the intervention, or in the absence of, network-level software of this kind
An object of the present invention is to provide a means by which wavelength configuration in a network may be simplified and/or automated and, WSS devices in a WDM optical network may be automatically configured at the WSS device and/or network node level without the drawbacks of network-level wavelength control.